The operator of a Washington rooming house for the elderly and infirm pleaded guilty in D.C. Superior Court yesterday to 10 counts of violating city health and safety laws. The facility was ordered closed last October.

Eunice Tally, 47, who appeared before Judge William S. Thompson, was charged last Oct. 26 with 27 violations after D.C. police officers and members of a special inspections force closed Tally's three rooming houses and evicted 16 mostly elderly residents.

Assistant D.C. Corporation Counsel Mark Mann, the prosecutor in the case, said the city agreed to drop 17 of the original charges in exchange for Tally's plea of guilty to the remaining 10. Tally, who will be sentenced Sept. 24, could be fined as much as $3,000 and could be sentenced to a jail term.

Charges against Tally included operating a "community residential facility" and a food establishment without a license and failure to provide proper fire safety equipment, sufficient heat and a supply of hot water at her houses at 1242-46 10th St. NW.

According to court records, city inspectors who entered Tally's home last October found several broken windows, heavy accumulations of dirt in residents' rooms, infestations of roaches and mice, and accumulation of oil on the basement floor and inoperative toilets.

Inspectors also found that Tally had knocked out basement walls under the three houses, creating a major fire hazard, according to court records. The houses were ordered closed by the D.C. fire marshal.

Tally's privately operated establishment was among about 400 group homes that were to be inspected by a special task force of city inspectors created by D.C. Mayor Marion Barry two days after 10 women were killed in a night-time fire that swept through a home at 1710 Lamont St. NW on April 11, 1979.

An inspection of Tally's residence was planned after police detectives investigating the death of a 65-year-old resident said they observed generally dilapidated and unsanitary conditions. The city medical examiner ruled that the man died of tuberculosis.